Cost-effective LFSR synthesis for optimal pseudoexhaustive BISTtest sets

The generation of pseudoexhaustive test sets for the built-in self-test (BIST) of combinational circuits is addressed, using as a test pattern generator a simple linear feedback register (LFSR), structure, known as LFSR/SR. It is shown that particular orderings of the LFSR cells can significantly reduce the test set size. In addition, it is shown that an LFSR/SK designed with a particular cell ordering and the allowance of a marginal number of additional cells guarantees pseudoexhaustive test sets of the minimum size 2^w, where w is the maximum input dependency limit of the circuit under test. Extensive experimentation on benchmark circuits and comparisons with the hardware overhead of other methods indicate the advantage of this approach